The term of art “thermochromic”, as used throughout this specification, generally refers to pigments or dyes which, when exposed to changes in temperature, experience a change in color. Similarly, the term “reversible” when used to describe such pigments or dyes, reflects that the color changes obtained during thermal cycling may be reversed. Thermochromic pigments or dyes (or generally “thermochromic agents”) are known in a variety of arts ranging from the field of novelty items to the medical industry. Generally, thermochromic agents are used to either add or create aesthetic effects with no practical purpose other than entertainment, or are used as an indicator, of sorts, to identify temperature changes in items in which the thermochromic agents are embodied or otherwise utilized.
For example, U.S. Pat. No. 5,219,625 (“Matsunami”) discloses the use of thermochromic materials for application to clothing and toys for entertainment purposes. On the opposite end of the spectrum, International Publication No. WO 2016/093788 (“Isildak”) teaches the use of thermochromic agents to image blood vessels, such as to identify cancerous tumors which (according to the publication) include higher densities of blood vessels, for example. U.S. Publication No. 2009/0143516 (“MacDonald”) also teaches the use of thermochromic agents in the medical field, but in the implementation of such agents into gloves, so as to be able to determine whether a surgical glove is punctured. In still other uses of thermochromic agents, U.S. Publication No. 2014/0291585 (“Tozuka”) teaches to introduce thermochromic agents into the ink of writing instruments, so that if a mistake is made while writing, the writing ink (which includes thermochromic pigment) can be heated through friction to make the ink visually disappear.
In addition to the above uses, there is limited knowledge in the art of the use of thermochromic agents in the field of temperature therapy. For example, U.S. Publication No. 2013/0073018 (“Harwood”) teaches the use of thermochromic films applied to a thermal pack “cover” or “covering” for notifying the user as to when the pack is ready for use. However, the Harwood reference has many disadvantages which the applicants herein have addressed or solved with the present application for invention. For example, a thermal pack covering is not an accurate representation of the temperature of the therapy pack, nor is it a reliable indicator that the therapy pack is ready for therapeutic use. A thermal pack covering is exposed to ambient air and is also exposed to the skin of a pack user, or to a refrigerator surface, or table, or other surface, which the covering contacts when the thermal pack is chilled for use or placed on a surface prior to use. Therefore, the thermal pack coverings taught in Harwood are likely to change color at times responsive to (or at least impacted by) ambient air or skin (or other surface) temperatures, in contrast to providing an accurate measure of the temperature of the “core” of the temperature therapy pack itself. Consequently, the user of a pack, such as disclosed in Harwood, is likely to be misled by the color changing features disclosed therein. This is particularly true of the embodiments disclosed in Harwood in which a thermochromic agent is introduced into a fabric cover which is enshrouded over the disclosed temperature therapy packs to impart a particular aesthetic appearance (see, i.e., Harwood, para. [0029]).
The “temperature exchange material” of a thermal pack is the payload of the thermal pack which stores the hot or cold temperature (heat, or lack thereof in the case of a cold pack) for transfer to the skin or body part of an end user. Notably, Harwood nowhere teaches to integrate thermochromic agents into the temperature exchange material of a thermal pack itself. Moreover, Harwood nowhere teaches how to technically implement such an integration into the thermal exchange material of a thermal pack, or how to manufacture such a thermal pack. In particular, the applicants of the present invention have discovered that there are numerous difficulties and obstacles in doing so.
The applicants of the present invention have also discovered problems in the prior art pertaining to hydrogels, including the durability of hydrogels in semi-solid or solid form. Moreover, the applicants of the inventions disclosed herein have discovered that there are needs in the art for hydrogels, in solid, semi-solid, and/or fluid gel form, which durably integrate thermochromic agents. More generally, applicants have also discovered a need for polymers which integrate thermochromic agents which have improved lifespans (e.g., in storage and otherwise) and/or which have increased numbers of available use cycles and/or which exhibit improved usage times.
In view of the above-identified deficiencies in the art, the applicants for the inventions described herein have addressed, overcome, or solved such deficiencies (in whole or in part) with one or more of the below described methods, processes, or apparatus. It is, in certain embodiments, a purpose of the herein described methods, processes, or apparatus to address one or more of the above deficiencies or needs in the art. It is also a purpose of the herein described methods, processes, or apparatus to address other drawbacks and/or other desires for improvements in the art, whether or not currently known, which will become more apparent to the skilled artisan once given the present disclosure.